It is common to produce netting by warp knitting on a Raschel type knitting machine. The Raschel type machine is capable of knitting from an array of yarn ends threaded through a number of guide bars which shog, or move laterally, as the knitting needles of the machine move vertically. The several guide bars are individually controlled in a manner so as to create a particular stitch pattern.
A net is typically formed with uniform sized diamond shaped openings separated by short sections where the outer corners of adjacent openings are joined together by cross-over stitches. The formation pattern is normally generated by means of a pattern chain which drives the guide bar shogging motion and is made up of a connected series of shaped cam links. These cam links may be replaced with links of a different shape so as to drive the guide bars differently and produce different knitting patterns. However, the operation of changing links and rebuilding a pattern chain is a time consuming one and cannot be efficiently done during a production run. Therefore, nets produced heretofore have been of uniform sized openings.
Knitted netting is created by a series of legs and a series of alternating joins. A leg is a knit cord made of a number of warp yarn ends knit together for a specified number of courses. A join is a crossover connection between two adjacent legs. In order for a particular leg to become one side of a diamond, joins must be made first at one end and then at the other end of the particular leg during knitting.
Ordinarily, a join is a much shorter stitch formation than a leg in a diamond pattern net configuration. It is possible, however, to knit a net with hexagonal, rather than diamond shaped openings, in which case a join is formed approximately the same length as a leg. The principles of the invention disclosed would be applicable to either a diamond or hexagonal shaped net opening.
While nets have been made in the basic manner described above for a long time, it has been a recognized but unsatisfied need to produce a netting with varied width. Frequently, prior art nets are modified from the initial rectangular shape in which they are knitted by the process of sewing sections together. This is usually done to create a net in which the openings and the width in the middle of the net are larger than at the ends of the net, and therefore the net is able to securely support the load in cradle-like fashion. As would be expected, a section of net joined by a stitched seam will tend to be weaker than an all-knit section.
Another reason to control the formation of diamonds in a knit net is to create a particular aesthetic appearance. It has been discovered in reference to the present invention, that by making alternating rows of small and large diamonds, or by gradually increasing and then decreasing the size of the diamonds, one can create a net of unique appearance.
The invention further recognizes that the possibility of varied openings, or orifice, netting potentially leads to applications in cargo nets, fish nets, sports nets and automobile use nets, i.e. nets generally intended to support or contain a load.
A modification of the traditional Raschel type knitting machine is disclosed in U.S. Pat. No. 4,364,244 to Vambutas, et al. for "Memory Controlled Electromagnetic Passive Controllers". The '244 patent teaches a programmable controller operative to actuate a number of solenoid coils which are each mechanically connected to a respective guide bar. The controller program determines solenoid motions and the consequent knit stitch pattern. A major drawback to this machine is that it requires an unusually expensive machine adaptation.
Therefore, an objective of the present invention is provide a knit netting in which the orifice or opening size is larger in one area than in another area.
An additional objective of the invention is to provide a net made on a warp knitting machine with openings of varying sizes.
A further objective of the invention is to be able to efficiently vary the size of diamond shaped openings in a net construction.
A still further objective of the invention is to create a net having alternating large and small openings.
These and other objectives will be apparent through the disclosure below.